| Year | Value (SE) |
|---|---|
| 2006 | 0.5656 (0.0933) |
| 2008 | 0.4548 (0.0698) |
| 2009 | 0.6080 (0.0598) |
| 2010 | 0.5935 (0.0488) |
| 2011 | 0.7769 (0.0693) |
| 2012 | 0.6411 (0.0728) |
| 2015 | 0.2350 (0.1532) |
| 2016 | 0.2497 (0.1688) |
| 2019 | 0.5670 (0.1937) |
| 2020 | 0.2608 (0.1040) |
| 2021 | 0.0881 (0.0638) |
| 2022 | 0.2689 (0.0739) |
| 2023 | 0.3235 (0.2351) |
